Stepping motor work and feed drive for magnetic tape recorder



M. J. H. STAAR STEPPING MOTOR WORK AND FEED DRIVE Jun 20, 1967 FORMAGNETIC TAPE RECORDER Original Filed March 22, 1962 7 Sheets-Sheet 1INVENTOR. MARCEL-JULES HELENE SUM/i BY wagzb,

'7 Sheets-Sheet STA/M? STEPPING MOTOR WORK AND FEED DRIVE FOR MAGNETICTAPE RECORDER 1962 June 26, 1967 Original Filed March 22,

INVENTOR.

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BY 7 Wag 160M $4.0

ZED U U I] MARCEL JULES HELENE STA/1R June 2Q, 1957 M. J. H. 5* AR 13 9STEPPING MOTOR WORK D FEED DRIVE i MAGNETIC TAPE RECORDER FOP OriginalFiled March 22, 1962 7 Sheets-Sheet 5 INV EN TOR.

MARCEL JULES HELENE STAAR 3,327,1&8

June 20, 1967 M. J. H. STAAR STEPPING MOTOR WORK AND FEED DRIVE FORMAGNETIC TAPE RECORDER 1962 I '7 Sheets-Sheet 4 Original Filed March 22,

@ziii INVENTOR.

ATTYS.

MARCEL JULES HELENE STAAR W. I E I y g v is 1 3 2s Q 3 fl Q NNT@\ 32% A3ms E5 m m mi June 20, 1967 M. J H. STAA'R 352K188 STEPPING MOTOR WORKAND FEED DRIVE FOR MAGNET-1C TAPE RECORDER Original Filed March 22, 19627 Sheets-Sheet 5 v B QL- -JLRLE E- MUM/'5 LRE- O OR+ 1 3+ --LRR y Ll?2-l-f+ o %WLATCHING RELAYS 1%- c NT/IVUOUS F DRIVE GMOTION 56 CAM L45 i? d;I all/0 I 9 L -IARM5 E as i 246 1 60 8+ SWITGH'L x STEPPING: MOTOR RELAYRR REL ERsE g PREFERENCE [96 H 5 6 SOLENOID 1 v k I V l v 92 L L jREVERSE C j B- R5 a Tr- JQ iJE RR 1 L P 66 LL \7P INVENTOR. RECORDREVERSE MARCEL JULES HELENE STAAR PLAYBAGK BY W9% /5 MM4( 4 G1 GM ATTYSJune 20, 1967 M, J, STAAR 3,3Z'Y,188

. STEPPING MOTOR WORK AND FEED DRIVE FOR MAGNETIC TAPE RECORDER OriginalFiled March 22, 1962 7 Sheets-Sheet 6 INVENTOR. MARCEL JULES HELENESTAAR WQ KL, MM, 1 41 s @W M. J. H S'EAAFQ STEPPLNG MOTOR WORK AND FIJEDDRIVE FOR MAGNETIC TAPE RECORDER 1962 June 2%, 196? 7 Sheets-Sheet 7'Original Filed March 22,

United States Patent 4 Claims. (a. 318-39) This application is adivision of my copending application Ser. No. 181,544, filed Mar. 22,1962, now Patent No. 3,254,245.

This invention relates to apparatus for sound recording and playback,and more particularly to tape drive mechanisms for dictating machinesand the like of the type described in Patent No. 3,124,360, entitled,Dictating Machine 'Drive Mechanism. In such machines a relatively wideband of magnetic tape is used for the recording medium and the recordingis in the form of longitudinally spaced transverse traces across thetape.

One object of the invention is to provide a tape drive mechanism adaptedfor operation in synchronism with reciprocation of the recording andplayback head of such machine and capable of smultaneously advancing thetape precisely and silently the same distance each step to insure thatthe synchronism between head and tape is continuously maintained.

Another object is to provide a tape drive mechanism capable of rapidadvancing motion to move the tape quickly so that a minimum interruptionis present in the transverse movement of the recording and playback headas each trace is reversed to prevent audible reflections thereof in therecording.

A further object is to provide a tape drive mechanism selectivelyoperable to obtain continuous tape stepping.

Another object is to provide a tape drive mechanism which is reversible,so that the tape can be moved continuously in either direction.

A further object is to provide a tape drive mechanism which issusceptible to manual operation, enabling movement of the tape manuallyin either direction, and without damage to the drive for the recordinghead or to the drive for the tape.

A further object is to provide a stepping motor device for such a tapedrive or the like which is of simplified, compact and lightconstruction, having relatively few moving parts, requiring low valuesof current to operate and self-starting and self-locking each step.

Other objects and advantages will become apparent as the followingdescription proceeds, taken in connection with the accompanyingdrawings, wherein:

FIGURE 1 is a fragmentary side elevation of an illustrative dictatingmachine having a tape drive means embodying the present invention;

FIG. 2 is an enlarged fragmentary longitudinal section taken looking atthe opposite side of the tape drive stepping motor in FIG. 1;

FIG. 3 is an enlarged diagrammatic plan view of the tape drivemechanism;

FIG. 3A and 3B show successive positions of advance of a drive sprocketfor the tape;

FIG. 4 is an exploded perspective view of the stepping motor devicestator and rotor components;

FIG. 5 is a sectional view of the stepping motor device, taken in theplane of lines 5-5 in FIG. 6;

FIG. 6 is a transverse sectional view of the stepping motor device withthe components shown in FIG. 4 assembled;

FIG. 7 is an enlarged view in side elevation of the preference means andthe stepping motor device also shown in FIG. 1;

FIG. 8 is a view like FIG. 7 with the preference means in reverseposition;

FIG. 9 is an enlarged fragmentary sectional view to show details of thepreference arm and is taken in the plane of lines 9--9 in FIG. 8;

FIG. 10 is a diagrammatic view of the tape drive mechanism, recordingand playback device, and control means therefor, of the dictatingmachine of FIG. 1;

FIG. 11 is a diagrammatic view of an alternative form of preferencemeans for the stepping motor and control therefor;

FIG. 12 is a view like FIG. 11, showing the preference means in advanceposition and the knife switch actuated.

While the invention is susceptible of various modifications andalternative constructions, illustrative embodiments have been shown inthe drawings and will be described below in considerable detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific forms disclosed, but on the contrary, theintention is to cover all modifications alternative constructions andequivalents falling Within the spirit and scope of the invention asexpressed in the appended claims.

T ape drive mechanism Upon more specific reference to the drawings, itwill be seen that the invention is there exemplified in an illustrativedictating machine 20 built in the form of a compact, lightweight unitadapted for recording or transcription. For details of the more generalconstructional features of the machine, reference may be made to thePatent No. 3,124,360 entitled: Dictating Machine Drive Mechanism. Ingeneral, such machine comprises a housing or casing having a fiat base24 (FIGS. 1 and on which the components of the machine are mounted bymeans including spaced brackets 26 between which a roll 28 of relativelywide tape 30 is rotationally mounted. The tape on the roll is carried ona spindle 32 on which the tape 30 is tightly wound and the end 33 of thespindle is rotationally carried in notches 34 in the brackets 26. Thetape is shown in FIG. 2 led from the roll 28 onto a fiat surface 40presented by a transversely extending fixed frame member 42 which issupported on the base plate 24 of the casing and therefrom onto asurface 43 provided by the housing. The tape 30 is guided past therecording head 44, as shown in FIG. 10, while being intermittentlyadvanced during the recording or transcription process by the tape drivemechanism which includes sprockets 45 engaged in perforations 46adjacent the margins of the tape.

A pivotally mounted bar 47 (FIGS. 1 and 2) extends transversely acrossthe machine above the tape and provides support for a transverselymovable knife 48 (shown in lowered position in FIG. 2) which is manuallyoperable to sever dictating bearing lengths of tape from the roll. Tofacilitate positioning the end of the tape 30 under thebar 46, thelatter is pivotally mounted so that it may be raised to an upwardposition. The tape 30 is advanced under the bar and along the flatsurfaces 40, 43 presented by the frame of the machine and the housingpast the transversely reciprocated recording and playback head 44 which,as shown in FIG. 10, is located directly under and in contact with thetape for recording purposes. Referring to FIG. 2, the bar 46 includes apressure plate 50 which is resiliently urged downward by means hereinshown as springs 52 and has a soft under surface 54 hearing directlyagainst the tape and holding it against the surfaces 40, 43 and inengagement with the sprockets 45. As herein shown, the tape 30 is in theform of a magnetizable layer on a backing or support of plastic film orlike material, having evenly spaced perforations 46 in the margins ofthe tape.

As illustrated diagrammatic-ally in FIG. 10, the recording and playbackhead 44 is supported on a pivotally mounted arm 56 which is reciprocatedtransversely by a drive mechanism indicated by the general referencenumeral 58. According to one of the features of the present invention,the drive for the tape comprises a stepping motor 60 adapted to advancethe tape 30 in even increments of movement connected through suitablegearing 62 to a shaft 64 carrying the sprockets 45 engaged in theperforations 46 of the tape. Synchronism between the reciprocatorymovement of the recording head 44 and the intermittent advance of thetape 30, is obtained by means of the control which is shown indiagrammatic form in FIG. thereby producing a recording on the tape inthe form (FIG. 3) of transverse arcuate traces T longitudinally spacedby the distance of each step of advance of the tape.

A separate microphone 66, shown diagrammatically in FIG. 10, isconnected by cable to the dictating machine and includes hand-operatedpush buttons 68, 70, 72 or the like for controlling the operation of themachine. A microphone 66, with hand-operated controls, as showndiagrammatically in FIG. 10, provides means for controlling theoperation of the machine for recording and playback immediately of therecorded information or dictation. Thus the dictating machine isactuated to record by means such as a button which may be shifted toRecord position which will start the recording process. The drive 58 forthe recording head 44 will be actuated responsive thereto to reciprocatethe head and the a tape 30 will be advanced step by step in synchronismwith the head 44. The tape 30 may be stopped by shifting the button 68from its Recor position and restarted at the option of the dictator.Such control on the microphone may provide for backspacing as well asfor advancing the tape. In the present instance this is achieved byshifting the button 72 to its Reverse position, and the controls foroperating the drive mechanism to cause the tape to be moved andbackspaced will be described more completely later.

It will also be understood that the machine may be set up fortranscribing a piece of dictation previously recorded on a length ofmagnetic tape. It will be noted that with the record in the form of ashort length of tape, the tape may be laid on the upper housing sectionto extend under the pivotal bar 47 which extends transversely across themachine. One of the major features of the machine is the provision ofmeans including the knife 48 supported by the bar 47 for movement acrossthe tape, for severing the tape after a piece of dictation has beencompleted so as to separate a dictation-bearing length of tape from theroll and to provide the record thereof in the form of a short length oftape. In this way, the record may be easily handled either to betranscribed, filed, or mailed in the usual mailing envelope. Thefacilitate handling the relatively short piece of tape, means areprovided to accurately align and guide the end of the tape in positionpast the sprockets and over the recording head. It will be understoodthat in keeping with usual practice, the operator transcribing with useof the machine may employ a headpiece, including earphone, and forlistening to the record may employ foot operated controls for advancingand backspacing the tape during the transcription process. It iscontemplated that the same machine will be used for both dictation andtranscription, separate means being provided for connecting thetranscription controls to the machine.

Turning now to the means for support and drive for the recording andplayback head 44, which is described in greater detail in the copendingapplication before referred to, the drive is shown diagrammatically inFIG. 10. Adjacent the outer or free end of the arm 56 is mounted arotary drive roller 74. The drive roller 74 is supported on a verticalaxis by means of a shaft having a pinion 76 at the upper end of theshaft which is in mesh with a worm gear 78 carried by a shaft powered bya motor 80 or suitable other power source on the arm 56. Electricalpower is supplied to the motor 80 from a power supply, so that the driveroller 74 is continuously operated by the motor when the machine isbeing used for recording or transcribing dictation.

The reciprocatory drive mechanism for the head also includes a slidableplate 82 which is carried fiat on the base 24 of the housing and isprovided with an arcuate slot 84 in which the drive roller is received.The plate 82 is movable in a direction axially of the tape, and isrestrained against transverse movement by means such as guides 85 on thesides of the plate, to position one wall of the slot 84-1 or the otherwall of the slot 842 in engagement with the drive roller 74 such thatupon continuous rotation of the drive roller by the motor 80 a reactionforce is set up tending to move the pivotal arm 54 in one direction orthe other. The drive roller 74 is shown in FIG. 10 in a neutral positionfree from engagement with either wall of the slot. By moving theslidable plate 82 upwardly in FIG. 10 to engage the drive roller withthe lower edge of the slot 84-1, upon normal counterclockwise rotationof the drive roller, the arm 56 and head 44 carried thereby will bepivoted from right to left as viewed in this figure. By moving the plate82 downwardly to position the drive roller in engagement with the upperwall of the slot 84-2, with the drive roller 74 operatingcounterclockwise, the arm and head will be driven from left to right.

For positioning the plate 82 to engage one Wall or the other wall of theslot with the drive roller 74, means are provided, showndiagrammatically in FIG. 10 as a pair of drive solenoids DSI, DS-Z,arranged normal to a pivot-ally mounted connecting lever 88 whichtransmits the motion of the solenoids to the slidable plate. In thepresent case, the connecting lever 88 is pivotally supported on a pin 90fixed to the base plate 24. Lost motion connection is provided betweenthe lever and the slidable plate by means of an elongated slot 92 in thelever and a pin 94 fixed to the plate. The solenoids for actuation ofthe slidable plate each include armatures DS1-A, DS2A which arepivotally mounted such that when one of the solenoids is energized topick up its armature, the latter pivots about an intermediate point ofsupport, the pivotal motion of the armature being transmitted by an armDSl-AA, =DS2-AA extending from the armature to the connecting lever. Forthis purpose the end of the connecting lever 88 adjacent the solenoidsDS1, DS2 has a pin 96 which fits between the arms carried by thesolenoid armatures. It is contemplated that one or the other of thesolenoids will be energized to shift the plate between alternatepositions of engagement.

The two drive solenoids DS1, DS2 which control the plate position andthus form components of the reciprocatory drive mechanism, are shown inthe diagrammatic view of FIG. 10 in positions corresponding to thepositions which they actually occupy in the dictating machine housing.Referring to this figure, it will be seen that the solenoids D81, D32connected to a source of supply indicated conventionally as B-{- via theconductor 93 and the normally closed contacts RR-l of the reverse relayRR, when either the Record or Playback switch of the microphone or likecontrol instrurnentality is closed. The circuit is completed through oneof the solenoids D81, D82 by means of alternately operated driveswitches DSWl, IDSWZ which are connected in series with the solenoidsand the return side of the circuit herein shown conventionally as B. Aswill be evident from FIG. 10, such switches DSWl, DSWZ are alternatelyoperated by a drive cam 100' on the sprocket shaft 102. The earn 100operates the switches via an actuator and is fully reversible. It willbe noted that with the circuit energized, and the microphone switch oneither the Record or Playback position, the plate '82 will be shifted toa position corresponding to a position of the sprocket shaft and thusthe tape.

Accordingly, with one of the drive solenoids DSl or DS2 of thereciprocatory drive mechanism energized, the recording and playback head44 will be driven in one direction or the other across the tape, andsuch movement will continue until the trace is completed. Responsive tothe completion of each trace, the other solenoid D51 or DS2 will beenergized to shift the plate 82 and reverse the direction of motion ofthe head.

For the purpose of alternately operating the drive solenoids D51 or D-S2for the reciprocatory drive mechanism responsive to the completion ofeach trace of the head, referring to FIG. 10, the arm 56 carriesadjacent the outer end of the arm a pair of electrically energizedswitch contacts 104. The contacts at the end of the arm 56 areenergized, as will be apparent from FIG. 10, via the conductor 106 whichenergizes the arm, upon closing either of the switch buttons on themicrophone labelled Record or Playback. In the course of the transversetrace of the arm, one of the contacts 104 thereon facing forward in thedirection of movement engages a switch member 108, 110 located adjacentthe end of the path of the arm to close a circuit. Thus, moving fromright to left as viewed in FIG. 10, the contact 104 on the lefthand sideof the arm 56 engages the switch member 108 positioned adjacent theleft-hand side of the plate. With the contacts 104 on the arm '56energized, the switch assemblies 108, 110 form a terminal which, asshown in FIG. 10, is connected in the control means to provide a signalresponsive to the completion of each trace of the arm. This is achievedin the present instance by connecting the switch assemblies 168, 110 toa pair of latching relays LR1, LR2. By means of the control circuitincluding the latching relays LRI, LR2, the tape drive and reciprocatingdrive for the head are synchronized. How this is achieved will be setout more completely later. At this point, it will be noted that in theoperation of the unit, with the sprocket shaft 102 positioned as shownin FIG. 10, and the upper drive solenoid DSl of the reciprocatory drivemechanism connected through the drive switch DSW1 to B--, the picking upof the armature of that solenoid D31 will move the drive plate 82upwardly as viewed in FIG. to engage the lower edge of the slot 34-1with the roller 74. With the roller 74 rotating counterclockwise, thiswill cause the arm 56 to sweep toward the left. Responsive to thecontact 104 at the end of the arm engaging the switch means 108 at theleft-hand side of the plate and adjacent the left end of the path of thearm, B+ will be connected through the conductor 112 connected to thatswitch, to the latching relay LR2 at the upper right-hand portion ofFIG. 17. It will be seen that the relay will be energized and heldenergized for a brief period by means of the condenser 114 across itsinput terminals, picking up a pair of contacts LR2-2, LR2.3 whichconnect the 13+ and B via conductors 116, 118 to means herein shown asthe stepping motor 60 for the tape drive. This effectively reverses thepolarization of the stator of the motor 60. How the reversal of polarityof the energizing current causes operation of the stepping motor, willbe considered in more detail in the following section. With the drivecam 1110 at the end of the sprocket shaft 1tl2 shifted ahead one stepfrom the position shown, the drive switches associated therewith will bemoved to its upper alternate position with tDSW-I closed, therebydeenergizing the first drive solenoid D81 and energizing the othersolenoid D82 thereby causing the plate 82 to be shifted in position toengage the upper edge 842 of the slot 84 with the drive roller 74,thereby reversing the direction of motion of the arm 56 so that it movesto the right as in FIG. 10. At the completion of the trace to the right,the switch 110 is energized to actuate the latching relay LRl, againreversing the polarity of current supplied over the conductors 1-16, 118 to the stepping motor 60. In this manner the head 44 is reciprocated,and responsive to the completion of each trace the polarity is reversedof the stator poles of the stepping motor 60.

Stepping motor According to one of the major features of the presentinvention, the tape drive mechanism is operated by a stepping motordevice 60 which, as shown in FIGS. 2 and 3 is connected to sprockets 45which are engaged in the perforations 46 in the tape by a gear train 62carried on the frame of the machine. Referring particularly to FIGS. 46,this stepping motor device 60 comprises a rotor which is supported on ahorizontal shaft 122 carried on the frame of the machine. The shaft 122carries a drive gear 124 (FIG. 2) fixed thereto of the gear train 6-2.conveying motion of the rotor 120' to the sprocket shaft 64. Referringagain to FIGS. 46, the rotor includes an annular ring made ofpermanently magnetized segments 126 labelled R-l to R-24. These segmentsare polarized such that adjacent segments (R-1 and R-2, for example)have the opposite polarity. The ring of rotor segments is fixed to ahand wheel 127 made of non-magnetizable material, such as plastic, whichhas an outer rim 128 spaced outwardly of the ring of segments 126forming the rotor. The outer rim 128 of the wheel 127 projects above theupper surface of the dictating machine housing (FIG. 2) and isaccessible for manual operation to rotate the sprocket shaft 64directly, having a corrugated or knurled outer surface to facilitatesuch manual operation.

The stator 130 of the stepping motor (FIG. 4) includes a plurality ofcircumferentially spaced, relatively narrow pole pieces 132 carried inan annular ring outside of the ring of rotor segments 126, one statorpole piece for each rotor segment. These pole pieces labelled 8-1 to8-24 in FIG. 5, are formed as parallel bars or teeth extending from apair of axially spaced plates 134, 136 parallel to the axis of thestepping motor shaft 122 and evenly spaced about the ring of rotorsegments. As shown in FIG. 4, the bars or teeth 8-1 to S-24 forming thestator pole pieces 132 are arranged so that every other tooth is carriedby the same plate 134 or 136 so that the teeth from one plate areinterposed between the teeth carried by the companion plate. In thepresent case, the number of teeth 132 and thus poles of the statorcorresponds to the number of permanent magnet segments 126 of the rotor.Referring to FIG. 4, the even numbered bars S-2 to S24 are carried bythe plate 134 while the odd numbered bars S1 to 8-23 are carried by theplate 136. The even numbered bars are longer so that, with the spacingof the plates 134, 136, the bars 132 extend for the same axial distanceadjacent the rotor segments 126.

Each stator pole piece 8-1 to S24 is part of a magnetic circuitincluding a stator coil C1 to C24. The coils are wound so that everyother stator tooth or pole piece has the same polarity and theinterposed tooth or pole piece has the opposite polarity, as indicatedby the arrows in FIG. 4. The flux paths of the magnetic fields set up inthe even numbered teeth 8-2 to S24 and plate 134 carrying said teethupon energization of the even numbered stator coils C2 to C24, willextend in the same direction, and similarly the flux paths of themagnetic fields set up in the odd numbered teeth 84 to S-23 and theplate 136 carrying said teeth, will extend in the same direction toprovide greater field strength in the stator pole pieces. To this endthe plates 134, 136 carrying the bars 132 are axially spaced on a hub140' of non-magnetic material to insulate the plates from each other,and the teeth are fixed to maintain predetermined gaps or spacestherebetween. The coils C1 to C-24 are wound on a spool 142 which isfixed on the hub 140.

Accordingly, it will be seen that for any polarization of the statorpoles 8-1 to S24 the rotor will have positions in which the permanentmagnet rotor segments R-l to R- '24 are located adjacent pole pieces ofthe stator having opposite polarity. Upon reversal of polarization ofthe stator poles, the rotor will be placed in an unstable condidionsince adjacent poles of the stator and segments of the rotor will havethe same polarity, tending to urge the rotor circumferentially in bothdirections. The instability will result in the rotor turning in whateverdirection it is initially started, by one step, to its new position.

Preference means.According to one of the important features of thepresent invention, means are provided to mechanically produce apreferenceurging the rotor 120 of the stepping motor 60 in one directionor the other. Means are provided for urging the rotor in either theforward-advance direction or in the reverse-back space direction. Forthis purpose, referring to FIGS. 1, 6 and 7-9, the outer face 150 of thehand wheel 127 of the stepping motor 60 includes a circle of evenlyspaced wells or openings 152-1 to 152-24, one for each rotor segment 126and, thus, rotor position. Mounted across this face of the steppingmotor wheel 127 is a preference arm 154 carrying a ball 156 adjacent itsouter end seating in one of the wells or openings 152-1 to 152-224 inthe face of the stepping motor wheel. As shown in FIGS. 7 and 8 the arm154 is pivotally mounted on the stepping motor shaft 122 so that it maybe pivoted slightly clockwise from the postion shown in FIG. 7 to theposition shown in FIG. 8, being resiliently held in the position shownin FIG. 7 by a tension spring 156. In this position of the preferencearm 154 the ball 156 is supported by the arm on the lower edge 158 ofthe opening 152-8 just under the ball in the face of the stepping motorwheel such that the ball, which is being resiliently held against theside of the Wheel, acts on the lower edge thereby offsetting the rotorby the angle a and tending to urge the wheel in the counterclockwisedirection. With this preference means active in the manner shown, uponreversal of polarity of the stator poles, the rotor will be givensufficient initial urging for it to advance one step whereupon the ball156 rides up out of the first opening 152-8 and down into the nextopening 152-7.

With this same preference means, the stepping motor '60 may becontrolled to step in the reverse direction. This is achieved bypivoting the preference arm 154 and ball 156 as shown in FIG. 8clockwise to move the ball to the opposite side 160 of the opening orwell 152-8 beneath the ball and bear against that side, therebyoffsetting the rotor 120 by the angle on, and tending to urge the wheelof the stepping motor in a clockwise direction. Via the gear means tothe sprocket shaft 64 of the tape drive mechanism, counterclockwiserotation of the stepping motor as viewed in FIG. 8 produces advancemotion of the tape and clockwise rotation of the stepping motor producesback spacing.

The position of the arm 154 which imparts the preference to the rotor120 of the stepping motor 60 to rotate in one direction or the other, isunder the control of a reverse solenoid RS which appears in FIGS. 1, 7and 8 and which also appears in the diagrammatic illustration of FIG.10. Referring first to FIG. 8, the end of the preference arm 154adjacent the solenoid RS is connected to be operated by the solenoidarmature RSA. A pivotal lever 162 is included in this connection. Thesolenoid armature RSA is a right-angle member, pivotally mounted at thecorner of the member such that when the armature is drawn up by theenergization of the solenoid, as shown in FIG. 8, the right-angleportion thereof 164 is moved upward to engage a set screw 166 on thepivotal lever 162, pivoting the latter counterclockwise about its pivot164 and causing clockwise rotation of the preference arm 154. Thepreference arm 154 is connected with a lost motion pin and slotconnection 168 to the lever 162.

Now referring to FIG. 10, the arrangement is shown diagrammatically inthis figure, including the reversing solenoid RS which, with thereversing switch 72 on the Alternative preference means embodimentReferring to FIGS. 11 and 12, according to a further feature of theinvention preference means is provided engaging the rim of the steppingmotor rotor 120 to offset the rotor by an angle a or oi to producerotation in a desired direction.

For this purpose, a preference arm 200 is mounted on the frame of themachine to engage the ridged outer surface 202 of the rotor 120. Asherein shown, the said outer surface has circumferentially spacedprojections 204 each having inclined forward and trailing edges 206,208. The preference arm carries a roller 210 contacting the outersurface 202 of the rotor at the edge of one of such projections therebyimparting a rotational force to the rotor 120 offsetting it by the anglea or a As shown in FIG. 11, the reverse solenoid RS is energized byclosing the reverse switch 72, thereby drawing up its armature RSAwhich, via the bent lever 212 and connecting lever 214, tends to pivotthe preference downward to the position shown in FIG. 11, wherein theroller 210 engages the trailing side 206 of a projection 204 causing therotor to be offset by the angle m in the reverse direction. Uponreversing stator polarity, the rotor 120 will be moved one step in theReverse direction.

Referring now to FIG. 12, the preference arm 200 is positioned to causethe rotor 120 to advance rather than backspace the tape. To this end thereverse switch 72 is open and the reverse solenoid is deenergized,allowing the tension spring 214 to raise the preference arm 200 such asto move the roller 210 carried thereby into engagement with the forwardedge 208 of the projection 206, offsetting the rotor 120 by the angle ain the direction which will cause the rotor 120 to rotate in the advancedirection.

Controls for continuous motion Consideration will now be given to afurther important feature of the invention, whereby the stepping motor60 may be caused to intermittently move in rapid step-bystep fashion ineither direction. In the normal operation of the dictating machine torecord dictation, the stepping motor 60 is operated responsive to thecompletion of each trace of the recording and playback head 44 toadvance the tape a precise distance, as herein shown, one-half of thedistance between center lines of adjacent perforations. For this purposethe latching relays LRl and LR2. are alternately operated upon thealternate energization of the switch means 108, by the contacts 104carried by the reciprocating arm 56 supporting the recording andplayback head 44. To cause the stepping motor to operate it is onlynecessary to energize the stator coils C-1 to 0-24 for a short intervalsufficient to reverse the polarity of the stator pole pieces 8-1 to 8-24and thereby create the instability of the rotor due to the similarpolarization of the rotor segments R-l to R-24. The rotor will rotate inthe direction dictated by the mechanical preference means. Continuedenergization of the stepping motor stator is not necessary since thepermanent magnet rotor segments R-l to R-24 link the adjacent polepieces 8-1 to 8-24 with the flux of the permanent magnet fields therebyresiliently maintaining and interlocking the stator and rotor incircumferential position with the stator pieces in alignment with therotor segments but for the slight circumferential movement produced bythe preference means.

It will be noted that a single step of the rotor 120 of the steppingmotor 60, in either direction, produces motion of the tape drivesprocket shaft 102 and corresponding motion of the drive cam 100 andchange in state of the drive switches DSWl, DSW2 for the drive solenoidsD81 and DS2. Also on the sprocket shaft 102 is the continuous motion cam240 which is similarly moved upon step movement of the rotor 120. Thecontinuous motion cam 240 controls, via an actuator 242, a pair ofcontinuous motion switches CSWI and CSW2 which are energized over acommon conductor 244 leading to a source of positive potential hereinshown as 13+, thorugh the Reverse switch 72 on the microphone. Thecommon conductor 244 is also energized from a source of positivepotential upon the closing of a knife switch 246, which is shown at theright-hand side of FIG. and also shown in FIG. 2. The control meansincluding the Reverse switch 72 and the continuous motion switches DSWland DSW2 provide means for rapid step-by-step movement of the steppingmotor in the reverse direction to backspace the tape. This provisionenables backspacing the tape 30 to a previously recorded section ofdictation in rapid-fire manner, and upon release of the Reverse button72 and actuating either the Record button 68 or the Playback button 70,the step-by-step advance motion of the stepping motor 60 will resume,synchronized with the reciprocation of the recording and playback head44. This synchronization is achieved by means including the drive cam100 on the sprocket shaft and associated drive switches DSWI and DSWZwhich automatically produce a direction of movement of the recording andplayback head 44 dependent upon tape position, such that a new recordingmay be made directly over the old trace T or the old trace may be playedback, and the head 44 will be moved in the same direction as it wasmoved when the trace was originally made.

The continuous motion switches CSWl and CSW2 are connected to theconductors 112 and 250 leading to the latching relays LR2 and LR1,respectively. With the common conductor 244 energized by means of eitherthe Reverse switch 72 or the knife switch 246, one or the other of thelatching relays LR1 or LR2 will be energized via the continuous motionswitches CSWI and CSW2. It will be noted that in the position shown inFIG. 10, the first switch CSWI is closed thereby energizing the firstlatching relay LR1 over the conductor 250, which will shift thedirection of polarization of the stepping motor stator poles 8-1 toS-24, causing the rotor 120 to move one step. The direction of rotationwill be dependent upon the state of the reverse solenoid RS, andassuming actuation thereof responsive to the closing of the Reverseswitch 72, the rotor 120 will step in the reverse direction. Such motionof the rotor will cause the Sprocket shaft 102 to move one step shiftingthe continuous motion cam 240 one step, changing the state of thecontinuous motion switches CSWI, CSW2, deactuating the first andactuating the second one of the latter. Responsive thereto the secondlatching relay LR2 will be energized, shifting the polarization of thestepping motor stator poles 8-1 to 3-24, causing the rotor to step inthe reverse direction. This rapid intermittent stepping will continuefor so long as the Reverse switch 72 remains actuated.

As an additional feature of the invention, means are provided to advancethe stepping motor 60 a predetermined number of steps, in rapidstep-by-step fashion as an incident to cocking the knife 48 prior toslicing oif shortlengths of tape, so as to advance the tape beforecutting thereby providing a margin between the end of the tape and thelast recording trace T. For this purpose, the stepping motor 60 iscontrolled to operate in a continuous step-by-step manner by meansherein shown to include the knife switch 246. As above noted, uponclosing the knife switch 246, the continuous motion switches CSWl andCSW2 are electrically energized over the conductor 244. The knife switch246, as shown in FIG. 2, comprises a pair of flexible members yieldinglysupporting contacts 280, 282. A bent lever 284, is pivotablecounterclockwiseabout its pivot 286 to engage the flexible members, asshown in FIG. 2, and thereby close the contacts 280, 282 responsive tomanual cocking of the knife 48. To this end, the knife 48 is supportedon a memher 286 slidably carried on the knife bar 47 and movablemanually lengthwise of the bar to move the knife into cocked position atone side of the tape and, as an incident to completing this movement, topivot the knife from a raised position above the tape to a loweredposition (FIG. 2) for slicing through the tape. Depending below theslidable knife supporting member 286 is a pin which engages in anactuating member 288 linked to the upper end of the knife lever 284 forcamming it forwardly to close the knife switch.

Responsive to such closing of the knife switch contact-s 280, 282,continuous step-by-step motion of the stepping motor will be produceddue to the energization of the continuous motion switches CSWI and CSW2.Since the reverse solenoid RS is deene-rgized, the stepping motor 60will operate in the tape advance direction. After a predetermined numberof steps, the knife switch is opened by means herein shown as a releasegear 290. The latter is carried by the knife lever 284 and upon switchclosing movement of the lever is brought into mesh with the drive gear124 on the shaft of the stepping motor. To cause release of the switch246, the release gear 290 includes a continuous, non-toothed section 292which is brought into engagement with the teeth of the drive gear 124after a number of steps of advance of the drive gear upon continuousstep-by-step motion of the stepping motor. Responsive to such engagementby the non-toothed section 292 of the release gear, the knife lever 284is force-d away from the drive gear far enough to move the spring 294over center, the said spring 294 completing the pivotal motion of theknife lever to its oft position, as shown in phantom in FIG. 2. Atorsion spring 296 fixed at one end and connected to the release gear290 to be stressed upon counterclockwise rotation of the latter by thedrive gear 124, serves as means to return the release gear clockwise toa start position from which it may be rotated to count out the desirednumber of advance steps of the stepping motor before release after knifeactuation. It will be noted that by having a different size release gearor one with a different number of teeth, means are provided for readilypreselecting the number of steps of the stepping motor which will betaken.

Referring to FIG. 12, a similar knife switch and release means thereforis shown including a release gear 290. Closing the knife switch in thearrangement depicted causes the terminals 296 and 298 of the continuousmotion switches CSWl and CSW2 to be continuously energized, therebycausing the state of polarization of the stator pole pieces 8-1 to 8-24to be shifted responsive to each successive step of the stepping motor.The latter is achieved through the continuous motion cam C and switchesassociated therewith, in a manner similar to that described inconnection with FIG. 10.

Summary of operation I While it is believed that the operation of thedictating machine described herein, and particularly the tape drive Imechanism and stepping motor thereof, will be clear from the foregoing,the operation will be briefly summarized.

From FIGS. 3, 3A and 3B it will be seen that the distance from centerline to center line of adjacent perforations in the tape is an evenmultiple of the longitudinal spacing between adjacent transverse traces.As therein shown, the tape is advanced one-half of the distance betweenthe center lines of adjacent perforations 46 each step of theintermittent drive and, hence, of the stepping motor 60. This isrepresented by FIGS. 3A and 3B which show the same sprocket 45 at oneside of the tape in successive positions. With this arrangement, eachtrace from left to right, as viewed in FIG. 3, begins substantially onthe center line of a perforation, and each trace from right to leftbegins substantially intermediate the perforations. It will be notedthat with this arrangement the direction of motion of the head isdependent upon the position of the tape 30. The position of the tape, inturn, is dependent upon the angular position of the sprocket shaft andthe position of the sprockets. Thus, when a short length of tape isplaced on the machine for transcribing, the length of tape isautomatically positioned so that the recording head, when the drive isstarted, will be travelling in the same direction as the head travelledwhen the trace was originally recorded. Similarly, the drive mechanismfor the tape and the direction of motion of the recording head aresynchronized during the recording process so that if the tape isbackspaced or moved ahead to shift between previously and presentlyrecorded pieces of dictation, the head will always be travelling in thesame direction when the tape is stopped as it travelled when the tracewas originally recorded. How the direction of motion of the recordinghead is made dependent upon tape position and sprocket shaft position,will be more readily apparent from FIG. 10. The drive cam 100 which iscarried on the end of the sprocket shaft 102, is shown in position withthe actuator for the drive switches DSWI and DSWZ riding on a high pointof the cam and thus closing the switch DSWI. The drive solenoid D51 isthereby energized. It will be noted that the high and low points on theperiphery of the drive cam 100 correspond to successive positions of thetape, and the total number of such cam and tape positions per revolutionof the drive cam 100 agrees with the number of rotor segments 126 andstator pole pieces 8-]; to -24. One step counterclockwise from thesprocket position as shown, the drive switches actuator will drop into anotch of the cam, thus closing the other drive switch DSWZ and openingthe first switch DSWI. This will change the state of the drive solenoidsD81 and DS2. In the position as shown, the drive switch DSWI, which isconnected to the B- or the return, connects the said B- to the upperdrive solenoid DSl which, when energized, will draw up its armature andthereby move the drive plate 82 in an upward direction, as viewed inFIG. 10. With the first drive solenoid DS1 energized and the drive plate82 moved thereby to the upward position, the recording arm and head 44move to the left. With the drive cam 100 in its other position and thedrive switches in their alternate position, after a single step ofadvance by the stepping motor, the other drive solenoid D82 will beenergized lowering the drive plate and causing the recording head 44 tomove to the right.

In addition, means are provided for synchronizing the reciprocatorydrive for the head with the tape drive so that the tape is automaticallyadvanced a single step upon the completion of each transverse tracethereby to produce a continuous succession of recording traces inalternate directions longitudinally spaced by the distance of advance ofthe stepping motor, as shown in FIG. 3. In the present instance, this isachieved by the circuit at the top of FIG. including the latching relaysLRl, LRZ and the switch means 108, 110 mounted on the frame of thedictating machine adjacent the ends of the path of the recording head.As shown in FIG. 10, with the recording' head moving in either directionfrom right to left, upon actuation of the switch means 108 at the leftend of the path, the switch means connects B+ with which the arm 56 isenergized to the right-hand latching relay LRZ. Energizing this relayLR2 connects the stepping motor 60 to the power supply thereby causingthe stepping motor to advance one step from its prior position.

To cause the stepping motor to operate it is only necessary to energizethe stepping motor 56 for a short interval sufiicient to reverse thepolarity of the stator pole pieces and thereby create the instability ofthe rotor due to the similar polarization of the rotor segments. Therotor will rotate in the direction dictated by the mechanical preferencemeans of FIGS. 7 and 8.

A single advance step of the stepping motor produces motion of the tapedrive and corresponding motion of the drive cam 100 and change in stateof the drive switches DSWl, DSW2 for the drive solenoids, therebyreversing the position of the drive plate and producing reversal indirection of motion of the recording head. With the head moving towardthe right, therefore, the motion of the arm 56 will continue until theswitch contacts carried by the arm engage the switch means at the end ofthe path of the arm connecting B+ with which the arm is energized, tothe left-hand latching relay LRl via the conductor 240. This relay LR1is energized to pick up its contacts LRl-Z, LRl-3 thereby connecting thepower supply to the stepping motor 60 but of the inverse polarity. Withthe stator pole piece polarities thus changed, the stepping motor willbe caused to advance one step, advancing the sprocket drive and therebythe tape one step; Producing a single step of advance of the sprocketshaft shifts the drive cam 100 thereby changing the state of the drivesolenoids D51, D82, thereby reversing the position of the drive plateand the direction of motion of the recording head.

Further in keeping with the present invention, the stepping motor 60 maybe caused to operate in continuous rather than intermittent step-by-stepmanner, in the reverse direction, upon actuation of the Reverse switch'72. Also, the stepping motor is caused to advance a predeterminednumber of steps responsive to cocking the tape severing knife 48, toadvance the tape prior to cut-oft and form a margin between the lastrecording trace and the newly formed end of the tape. For this purpose,the continuous motion cam C, having a number of projections on itsperiphery equal to the stator and rotor poles of the same polarity, isturned by the rotor each step of the latter by a corresponding angle,resulting in reversal of the state of the continuous motion switchesCSW1 and and CSW2. Responsive to each such change of state of thecontinuous motion switches CSW1 and CSWZ, the polarity of the supplycurrent to the stator windings C-1 to C-24 is reversed, thereby causingthe stepping motor rotor 120 to advance a step. Rapid step-by-stepmotion is thus achieved until terminated by opening the Reverse switch22 or automatically, after a predetermined number of steps, by therelease means associated with the knife switch.

I claim as my invention:

1. In apparatus for sound recording and playback on a relative wide bandof magnetic tape, including a reciprocable recording and playback head,the combination comprising, a stepping motor having a rotor and a fixedstator, means connecting said rotor for intermittently moving the tape,said rotor including an annular ring of permanent magnet segments withadjacent segments being oppositely polarized, said stator including afixed ring of magnetizable pole pieces carried concentric with said ringof rotor segments, and windings associated with said stator pole piecesfor producing electromagnetic fields linking the latter, said windingsbeing constructed so that adjacent stator pole pieces are oppositelypolarized, said rotor being stepped responsive to reversing the polarityof said stator pole pieces in synchronism with the reciprocation of thehead, and means for energizing said windings including an electricalcircuit comprising a pair of latching relays having contacts forconnecting a source of potential to said stator windings, and means foralternately energizing said latching relays upon completion of eachtrace of the head thereby to reverse the polarity of said statorwindings and pole pieces.

2. In apparatus for sound recording and playback on a relatively wideband of magnetic tape, wherein the recording is in the form oflongitudinally spaced transverse traces across the tape, the combinationcomprising, a stepping motor having a rotor and a fixed stator, meansconnecting said rotor for moving the tape, said rotor including anannular ring of magnet segments with adjacent segments being oppositelypolarized, said stator including a ring of magnetizable pole piecescarried concentric with said rotor segments, windings associated withsaid stator pole pieces for producing electromagnetic fields linking thelatter, said windings being constructed so that adjacent stator polepieces are oppositely polarized, said rotor being stepped responsive toreversing the polarity of said stator pole pieces, and means forenergizing said windings including a reversing switch, actuating meansfor changing the state of said reversing switch thereby to reverse thepolarity of said stator pole pieces including a cam operated by saidrotor having a number of spaced teeth around the periphery of said camwith the number of teeth agreeing with the number of rotor poles havingthe same polarity so that upon each step of the rotor said cam turnsthrough a corresponding angle effective via said actuating means tochange the state of said reversing switch and produce continuousstep-by-step movement of the rotor.

3. In apparatus for sound recording and playback on a relatively wideband of magnetic tape, wherein the recording is in the form oflongitudinally spaced transverse traces across the tape, the combinationcomprising, a stepping motor having a rotor and a fixed stator, meansconnecting said rotor for moving said tape, said stator including aplurality of pole pieces having windings for polarizing the latter, saidrotor being stepped in a forward direction to advance the taperesponsive to reversing of the polarity of said stator pole pieces bymeans including an oscillating recording head, means producingcontinuous, high speed backstepping movement of the tape including meansfor reversing the polarity of said windings and stator pole piecesresponsive to each successive step of the rotor, and means forterminating said continuous high speed backstepping movement after apredetermined number of backsteps of the rotor.

4. In apparatus for sound recording and playback on a relatively wideband of magnetic tape, wherein the recording is in the form oflongitudinally spaced transverse stepping motor having a rotor and afixed stator, means connecting said rotor for moving said tape, saidstator including a plurality of pole pieces having windings forpolarizing the latter, said rotor being stepped responsive to reversingof the polarity of said stator pole pieces, means producing continuousstep-by-step movement of the tape including an energizing switch movableto a closed position for connecting a source of potential to saidwindings, an actuator for said switch, means for reversing polarity ofsaid windings and stator pole pieces responsive to each successive stepof the rotor, thereby producing continuous step-by-step movement of therotor, and means for terminating said continuous step-by-step movementincluding a drive gear operated by the rotor, a release gear carried bysaid energizing switch actuator and movable into mesh with said drivegear upon movement of said actuator to close said energizing switch,said release gear having a non-toothed portion rotated into engagementwith the teeth of said drive gear responsive to a predetermined numberof steps of said rotor thereby to shift said release gear out of meshwith said drive gear and responsive thereto to move said actuator toopen said energizing switch.

References Cited UNITED STATES PATENTS 2,474,829 7/ 1949 Curtis 318- X2,854,856 10/1958 Oppen 318-162 X 3,013,857 12/1961 Mufily 318-314 X3,037,202 5/ 1962' McNaney 318-312 X 3,217,221 11/ 1965 Heggen et al310-49 X ORIS L. RADER, Primary Examiner.

traces across the tape, the combination comprising, a 5 T. LYNCH,Assistant Examiner.

1. IN APPARATUS FOR SOUND RECORDING AND PLAYBACK ON A RELATIVE WIDE BANDOF MAGNETIC TAPE, INCLUDING A RECIPROCABLE RECORDING AND PLAYBACK HEAD,THE COMBINATION COMPRISING, A STEPPING MOTOR HAVING A ROTOR AND A FIXEDSTATOR, MEANS CONNECTING SAID ROTOR FOR INTERMITTENTLY MOVING THE TAPE,SAID ROTOR INCLUDING AN ANNULAR RING OF PERMANENT MAGNET SEGMENTS WITHADJACENT SEGMENTS BEING OPPOSITELY POLARIZED, SAID STATOR INCLUDING AFIXED RING OF MAGNETIZABLE POLE PIECES CARRIED CONCENTRIC WITH SAID RINGOF ROTOR SEGMENTS, AND WINDINGS ASSOCIATED WITH SAID STATOR POLE PIECESFOR PRODUCING ELECTROMAGNETIC FIELDS LINKING THE LATTER, SAID WINDINGSBEING CONSTRUCTED SO THAT ADJACENT STATOR POLE PIECES ARE OPPOSITELYPOLARIZED, SAID